Fluid pressure operated disk brake with automatic wear compensation



Feb. 13, 1951 H. J. BUTLER 2,541,032

FLUID PRESSURE OPERATED DISK BRAKE WITH AUTOMATIC WEAR COMPENSATION 2Sheets-Sheet 1 Filed Sept. 14, 1946 a D. E w 1 5w 0, "M Amw 1 W/E 2 w aa w a fl ME 6 d 1 E -u m w E .1 on Hfi w u v Q 2 a 1 n n a NM "M n, 3%.M. \L\

Feb. 13, 1951 H. J. BUTLER 2,541,032

. FLUID PRESSURE OPERATED DISK BRAKE WITH AUTOMATIC WEAR COMPENSATIONFiled Sept. 14, 1946 2 Sheets-Sheet 2 Patented Feb. 13, 1951 'iEUNlZIZEDrarer-Es FiTRAT'ENT OFFICE FLUID"PRESSUREOPERATED DISK .BRAKE W ITHAUTOMATIC WEAR- COMPENSATION v Henry JamesaButler, SuttonGoldfieldfEngland, assignorwtoiDunlop Rubber. Company Limited, county ofLondon; England, aiBritish' eompany Application-September 14,1946SerialNOQ 697,015

E' .-'In:Great Britain July 25, 1946 compensating for lsuch-wearofmtheiriction suras .m'ayrtake place in orderathat a minimum."Ycl'earance: as. aforesaid. maytbe retained.

Elie: :present invention has for: its object .to eprovide an: improved vmeans for. compensating automatically for wear of the friction surfacesin brakes as aforesaid.

ikAccording to. the inventiomfluidmperated' disc 5 brakes :of theqtypeehaving rotatable and non- :q'iotatable-. rbraking-...-elements.are provided whichccomprisea-zbrakeeapplying member in frictionalengagement -=with :sprngeoperated retraction nmeans whicnis deformed o1:displaced by move- ..;.ment 'ofsaidvmember to applyvbraking pressure.saidmember. inaexcess of a predetermined aamount,'thereby compensatingfor wear of the .i-braking elements.

mile-invention. will now. be described with par- Izticularnreference.to...the.. accompanying. drawings r.which illustrateihe.invention asapplied to an eaircraft brakingsystem.

Eigure Lis-lapart sectional-side elevationbf n a brake operating meansembodying a preferred eform-ofmyinvention.

I Figure 21s anendvview of part of Figure 1Z100kingfiromthe right .ofsaid figure.

,cFigure'I 3..1's a.fragmentary view' illustrating a amodi-fication. ofthe arrangement. illustrated'in Eigurel.

i i EigureAl is a sectional view of another brake operating-- means.embodying .the" invention.

liFigur'dis an end elevation ofpartofF'igur 4 -...lo'oking in. thedirectionbf the arrow in the said Ljfigure and Figure 6 is a'fragmentary'viewon'an enlarged scaleshowing the means of securing'theclampingplate tothe associated part of the apparatus "in'the'arrangement illustrated'in-Figures 4 and 5.

"In"the*drawings','like numerals of reference "in'dicate' similar oranalogousp'arts in theseveral views.

In the'form illustrated in 'Figures l and" 2" "of "the drawings, each ofthe hydraulically operated l "and which slips. on said. member onmovement of 2 1=-1a:of-a spider 1, and associated with this a'rm Ta hisa pin 8Whi Ch' passes through a space between two annuli9 and it whichare non-rotatable-but axially displaceable relatively to an aircraftwheel 15 I l' inthe manner disclosed in U; S. application SersNo;69.7;014'; filed September 14', 1946.

."The -pin 8 isdprovided with a head 'Baand mounted. orrthe-pin" 8-adjacent to the head Sa .wis-ta "cup shapedmember I2, which is embracedas a consequeneeeprovision .should-bemade for 10 by thecircumferentialw'all I30, of a sleeve l3 the pressure exerting face [3bof which is=in abutment with-the presented faces of"a""brake' padMacadam-ted toexert a braking effort on'the ad- -jacent-: faces 'of theannuli S and H]. A'similar 15. brake pad- Mb is located; ontheoppositeside'of the annuli 9 and i0.

rescaling rings 18- areiinserted in grooves in the :member 12* so as toensure a' fluid'tigiht sealing r betweenthe. circumferential wall 13a ofthe sleeve 1120 I 3 and the adjacent surface ofvthe membenll sealingringI 72 is locatedwithin 'arr inwardly directed centrally"disposed portion130 of the r-sleeve=|3 by meansof a cover plate ill and a'split ii-ringH. -=A sealing ring la is interposed between the fheadeflaa and thebottom of the recessin the a-memberl2=within-whichit is disposedin'order toefiect a fluid tight seal between the" relevant ppants.

The circumferential wall 13a" of the sleeve is enclosed within anenvelope" ifi 'having acor- 'rugated bottom 19a and a circumferentialwall 1 libs-which iswclamped-= in frictional engagement with. thevwallll Sid-of the sleeve 13 by-meansrof' a split camp 20 which may betightened up byaa bolt Hand arnut 22,-said envelope I e being-made of-arelatively resilient material and being-capa- ..b1e of being flexed.

Fluid is introducedinto the space between the s presented surfacesof-the sleeve IS- and'of'Ithe member l2 by way of an axial-bore il c'formed einltheipinfi.

. operationwhen fluid pressure is introduced -intol-themspaceaforesaid'the sleeve l 3 "isidismplaced: relatively *to' themember l2and caused to-apply braking pressure to the brake pads Ma, Mb. lThisdisplacement of'fithe sleeve" l3 rela- :1; tively to 'thememberlioccasions a slight flexing of .the'bottom i Swof the envelopeawhichflexing -ismfacilitatedwby xthe corrugations of the said bottomI911. Thusion the release"ofpressure'the inherent "-resiliencyintheenvelope l9 acts-as a returrrspring'and' restores the sleeve '13 to theinitial position.

It should be understood however that the degree is very small as onlysufficient return movement of the sleeve I3 is required as is necessaryto permit of the free running of the annuli 9 and I between the blocksMa, I lb when the fluid pressure is relieved.

In the event of the Wear of the brake pads I la, Mb, the sleeve I3 mustnormally be further disp aced by an amount equal to that wear. Thedegree of flexing of the envelope I9 is however insufficient to allowfor any additional movement of the sleeve I3 but alternatively thesleeve is free struction the envelope I9 is nonyie ding and slidablymounted within the end of the pin 8 is a plunger 8d having a domed head8e adapted to abut a complementary shaped portion of the envelope I9.Interposed between the domed head 8e and the adjacent end of the pin 8is a spring washer 23. A sealing ring. I I2 is located by a split ringIll lying within the lip I I3 of the portion I30.

In operation when braking pressure is applied the spring Washer 23 iscompressed so that upon the release of pressure the stored energv comesinto operation to restore the parts to their initial position.

In the event again of Wear of the frictional surfaces slip takes placebetween the sleeve I 3 and the envelope I9 so as to compenateautomatically for such wear.

In the arrangement illustrated in Figures 4-6 the sleeve I3 isexternally disposed and is frictionally engaged by a split clamp 20associated with a plate 24. Seals I3I and HI a are provided between theportion 'Ib' and the sleevelt and pin 8. The plate 24 is secured to thearm Ia of the spider by means of bolts 25 the shanks of which passthrough and are slidable within holes 24a adjacent to the corners of thesaid plate 24 and interposed between the heads of the bolts 25 and thebottoms of the recesses bounding the holes in the plate 24 through whichthe bolts 25 pass are spring washers 25 conveniently of the Bel evilletype.

Fluid pressure is introduced into the space between the inner surface ofthe head of the sleeve I3 and the complementary block 11) by way of apassage 2? which communicates with a source of pressure fluid throu h anannular passage 29 having a sealing ring 29 I.

In this construction two sets of annuli 9 and in are employed and on theapplication of fluid pressure the sleeve I3 is displaced relatively tothe block lb thereby applying braking pressure to brake pads I la, Mband Me. At the same time the displacement of the sleeve I3 occasions acompression of the spring washers 26 so that upon the release ofpressure the energy stored in the said spring 26 comes into operation torestore the sleeve I3 to its initial position.

In the event of wear of the frictional surfaces slip again can takeplace between the sleeve I3 and the clamp 2!! in order to permit of anautomatic increase of the volume of the liquid filled space tocompensate for the wear of the frictional surfaces and thus maintainsubstantially constant the degree of displacement permitted betweenthesleeve and the block lb.

Having described my invention, what I claim is:

1. Fluid pressure operated disc brakes which comprise inner and outerannular brake discs, said discs being spaced radially apart and capableof limited axial displacement, a fixed annular braking element disposedon one side of said discs, an axially displaceable annular brakingelement disposed on the opposite side of said discs to contact at anyinstant with only a portion of the braking area of said discs, andfluid-pressure operated piston and cylinder mechanism mounted to effectfrictional contact between said discs and said elements, said mechanismcomprising a brake-applying member engaging one face of saiddisplaceable braking element and having an axially extending skirt, acup-shaped member in fluid-tight engagement with the inner wall of saidskirt and defining with said brake-applying member a chamber forpressure fluid, an axially extending pin passing through the centers ofsaid displaceable braking members and elements and between said discsand engaging with the outer face of said cup-shaped member to restrainit from outward movement, and retraction means comprising an envelope infrictional engagement with the outer wall of said skirt to slip on saidbrake applying member when brake-applying movement of said memberexceeds a predetermined amount.

2. Fund-o erated disc brakes according to claim 1 wherein a plurality ofsets of fixed and axially elements are symmetrically disposed around thebraking surfaces brake discs.

3. Fluid pressure operated disc brakes which comprise a plurality ofinner and outer annular brake discs, said inner and outer discs beingspaced radially apart and capable of limited axial displacement, a fixedannular braking element and an outer axially displaceable brakingelement disposed adjacent the external surfaces of said plurality ofdiscs and an inner axially dis-' placeable braking element disposedbetween each pair of discs, said elements being relatively movaeffectfrictional contact between said discs and 7 said elements, saidmechanism comprising a brake-applying member engaging one face of saidouter displaceable braking element and having an axially extendingskirt, a cup-shaped member fluid-tight engagement with the inner wall ofsaid skirt and defining with said brake-applying member a chamber forpressure fluid, an axially extending pin passing through the centers ofsaid members and elements and between said discs and engaging with theouter face of said cupshaped member to restrain it from outwardmovement, and retraction means comprising an envelope in frictionalengagement with .the outer wall of said skirt to slip on saidbrake-applying member when brake-applying movement Of said memberexceeds a predetermined amount.

l. Fluid pressure operated disc brakes which comprise inner and outer,axially displaceable, annular brake discs, a pair of non-rotatablebraking elements disposed on opposite sides of said discs and extendinless than the circumference of said discs, one of said elements beindisplaceable axially toward the other and fluid pressure operated pistonand cylinder mechanism of the to move said displaceable element towardthe other element to efiect frictional contact between said discs andsaid elements, said mechanism comprising a brake applying memberengaging one face of the displaceable braking element and retractionmeans including a spring loaded cover having a slidable frictionalengagement with said displaceable braking element to slip thereon whensaid brake applying member moves beyond a predetermined distance.

5. Fluid pressure operated disc brakes which comprise inner and outerrotatable axially displaceable annular brake discs, a fixed brakingelement on one side of said discs and an axially displaceable brakingelement on the opposite side of said discs, said elements extending overonly a part of the circumference of said discs, a fluid pressureoperated mechanism to move said displaceable braking element toward saidfixed elements to efiect frictional contact between said discs and saidelements, said fluid pressure operated mechanism comprising a fixedpiston member, a cover slidably fitted over said piston, a pin connectedto said cover and passing through said piston and connected to saidaxially movable braking element, and a flanged sleeve memberfrictionally gripping the outer wall of said cover and adapted to permitsaid cover to slip when movement of said braking member exceeds apredetermined amount, said flanged sleeve member being secured to thepiston by spring loaded means to permit a limited axial movement.

6. The apparatus of claim 4 havin a plurality of braking elements andfluid pressure operated mechanism arranged in circumference series, the

total circumferential extent of said elements on said discs being lessthan the circumference of said discs.

'7. A brake applying member which comprises an open ended cylinder, apiston in said cylinder having an extension through the open end of saidcylinder, and a flexible envelope having a slidable frictionalengagement with the periphcry or" said cylinder and extending over theend of said piston, said envelope engaging the center part of saidpiston and being slightly spaced from the outer parts to flex under alimited movement or said piston and then being engaged to slide on saidcylinder upon further movement of said piston.

HENRY JAMES BUTLER.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,138,206 Rasmussen et al. Nov.29, 1938 2,146,009 Chase Feb. 7, 1939 2,189,134 Chard Feb. 6, 19402,234,689 Chard Mar. 11, 1941 2,274,885 Brown Mar. 3, 1942 2,319,231Hawley May 18, 1943 2,358,740 Scott-Iversen Sept. 19, 1944 2,366,993Forbes Dec. 26, 1944 2,371,554 Scott-Iversen Mar. 13, 1945 2,392,970Brisker Jan. 15, 1946 2,419,113 Bricker Apr. 15, 1947

